1. Field of the Invention
The present invention relates to an image forming apparatus such as a dye-sublimation, dye-sublimation laser, thermal transfer, or electrophotographic one.
2. Description of the Prior Art
Dye-sublimation image forming apparatuses, for example, are adapted to perform predetermined printing (e.g. color printing) by laying an ink ribbon with sublimation dye applied thereto on printing paper, applying electrical energy according to image information to a heat-sensitive head (thermal head), and sublimating and transferring the sublimation dye applied to the ink ribbon onto the special-purpose printing paper using thermal energy generated from the heat-sensitive head. Thus, such dye-sublimation image forming apparatuses are adapted to control, for example, the amount of energization of the heat-sensitive head, that is, the amount of heat generation in the head to reproduce a tonal image, attracting wide attention as capable of reproducing a high-quality color image yet with a small size and a simple structure.
Meanwhile, this kind of image forming apparatus is required to use special-purpose printing paper with an absorbing layer made of material for thermal transfer recording formed thereon. There have been marketed such printing papers that may be used as postcards by, for example, printing a photo on one surface (first surface) with an absorbing layer formed thereon, while a postal documentation area composed of a stamp portion and/or a zip code portion is printed preliminarily on the other surface (second surface).
However, when setting such printing paper with a postal documentation area printed on the second surface thereof in a paper feed cartridge of an image forming apparatus to print a photo on the first surface thereof, it is difficult to determine whether the printing paper should be arranged in either longitudinal or lateral direction with respect to the paper feed direction of the paper feed cartridge. It is only necessary to perform test printing in advance to avoid this difficulty, but special-purpose printing papers with an absorbing layer formed thereon to be used in this kind of image forming apparatus are extremely expensive relative to plain papers to be used in normal ink-jet image forming apparatuses, and test printing will waste expensive printing paper and ink ribbon, being extremely uneconomical. Further, although it can be considered to use plain paper as printing paper, plain paper, if used, will be attached firmly and undetachably to the ink ribbon in this kind of image forming apparatus, which makes it impossible to use plain paper. It is therefore impossible to perform test printing using inexpensive plain paper.
There has conventionally been proposed, for example, a double-sided image forming apparatus in which a print controller is adapted to direct printing of a first symbol, in a printing operation, that indicates whether one surface of paper that has already been printed should be arranged in either longitudinal or lateral direction with respect to the paper feed direction of a paper feed cartridge, and whether the paper should be set in the paper feed cartridge with the one surface that has already been printed up or down, when resetting the paper in the paper feed cartridge to print the other surface thereof (refer to Japanese Patent Laid-Open Publication No. 2000-255113 for example).
There has also been proposed a to-be-printed matter composed of sheets of cut paper with an identification mark for identifying the direction of the to-be-printed matter provided in one cut corner thereof (refer to Japanese Patent Laid-Open Publication No. Hei 11-245549 for example).
However, the arrangement described in Japanese Patent Laid-Open Publication No. 2000-255113 suffers from the following problems. In the image forming apparatus, since the print controller is adapted to direct printing of a first symbol that indicates whether paper should be set in the paper feed cartridge with one surface that has already been printed up or down, it is inevitably necessary to print the both surfaces of the paper. Therefore, when applying the arrangement to, for example, a dye-sublimation image forming apparatus, it is necessary to use printing paper with absorbing layers made of material for thermal transfer recording formed on the both surfaces thereof, even though a tonal image such as a photo is to be printed only on one surface. This consequently requires expensive printing paper to be used and the print controller to have a specific function of printing a first symbol, which causes the image forming apparatus itself to be complicated and expensive. Further, a first symbol is to be printed even in a margin, resulting in a poor appearance after the printing operation.
Also, the arrangement described in Japanese Patent Laid-Open Publication No. Hei 11-245549 suffers from a problem in that the identification mark is only for verifying that the to-be-printed matter is stacked infallibly in the same direction, and cannot identify the set direction with respect to the paper feed cartridge.